On 3/24/2012 9:22 AM, Mxsmanic wrote:
The sources I'm recording (traffic noises and other urban noise) tend to be
highly unpredictable, and often I end up recording with the meter hovering
around -12 dB or even -20 dB just to avoid clipping when the occasional car
horn honks or a motor scooter goes by.
There's nothing at all wrong with that. But consider this -
do you want the background noise, or is that car horn or
motor scooter really important and something that you want
to save? If it is, then you either need to allow for it, or
engage a limiter to sit on those unexpected sounds that are
much higher than your background level if it sounds OK. If
you don't care about those random loud sounds, let 'em clip
and just edit them out.
The TASCAM DR-40, and maybe you can do the same trick with
other recorders that can record 4 tracks, lets you set up a
second pair of tracks recording at a lower level than your
primary set. If something overloads on your primary tracks,
chances are it'll be OK on the tracks with lower gain, and
you can edit between the two sets of tracks. The Sony
PCM-D50's limiter actually works like this automatically. It
records a buffer 10 or 20 dB below the main track. When it
detects an overload, it automatically replaces the
overloaded section with the backup and then normalizes the
spliced-in segment so it will go to full scale. It's really
cool.
One things that surprises me is that the sounds that I would expect to see
hitting 0 dB often do not, whereas the sounds that I would not expect to see
clipped are in fact being clipped. For example, car horns don't seem to be as
loud as they sound to my ears, but sometimes the rumble of a passing bus
actually reaches 0 dB even though it doesn't seem that loud.
That's because a car horn is a designed sound. It's supposed
to be easy to hear, which means that it sounds louder than
it actually is, though I've measured passing fire engines at
100 dB SPL when their sirens are going. A bus has a lot of
low frequency energy that moves a lot of air, but your ear
is less sensitive than an A/D converter in that frequency
range.
--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson
http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff